From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27775C433DF for ; Mon, 17 Aug 2020 17:04:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 04176206FA for ; Mon, 17 Aug 2020 17:04:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597683876; bh=fW0PLUaemraPxR56ZlLLDoiTZLlCiLqb4+qpdqoPWUg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=NFdohHar4NM/fayYZ/RSede6wSHuExeeLbhyU6UmY+R4OOYE5nLeV+syovIMLC36Y /hgjTIoCEAoIfEMf/BypNuMlVI5pGJHgrIzdbNUlJLqCSidk6nuCQOezRUDPvOW/1Y ai4Byw8Giq+7/d9mfRJ5sizAW6TEpfneK2O1O/J8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731082AbgHQREd (ORCPT ); Mon, 17 Aug 2020 13:04:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:60452 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388501AbgHQQJV (ORCPT ); Mon, 17 Aug 2020 12:09:21 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B43C220658; Mon, 17 Aug 2020 16:09:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597680558; bh=fW0PLUaemraPxR56ZlLLDoiTZLlCiLqb4+qpdqoPWUg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=quAarE4ORPWpKpjdlyBZB6/4bsxmFfCatHgSAKiQGi6bwZnaNR+PSaajVB+5xSOwp oy8Erj+IeQNiu8TyEQZSQFsuGI05zEg4ig/IkeIOCDvOsnukhsdg19WoJ5CnKpU2dA lHOWYu28h0WNIkzpR4SS2bwMFhDitUthh/grKHq8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+6bed2d543cf7e48b822b@syzkaller.appspotmail.com, Tuomas Tynkkynen , Hans Verkuil , Sakari Ailus , Mauro Carvalho Chehab Subject: [PATCH 5.4 235/270] media: media-request: Fix crash if memory allocation fails Date: Mon, 17 Aug 2020 17:17:16 +0200 Message-Id: <20200817143807.509404066@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200817143755.807583758@linuxfoundation.org> References: <20200817143755.807583758@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tuomas Tynkkynen commit e30cc79cc80fd919b697a15c5000d9f57487de8e upstream. Syzbot reports a NULL-ptr deref in the kref_put() call: BUG: KASAN: null-ptr-deref in media_request_put drivers/media/mc/mc-request.c:81 [inline] kref_put include/linux/kref.h:64 [inline] media_request_put drivers/media/mc/mc-request.c:81 [inline] media_request_close+0x4d/0x170 drivers/media/mc/mc-request.c:89 __fput+0x2ed/0x750 fs/file_table.c:281 task_work_run+0x147/0x1d0 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop arch/x86/entry/common.c:165 [inline] prepare_exit_to_usermode+0x48e/0x600 arch/x86/entry/common.c:196 What led to this crash was an injected memory allocation failure in media_request_alloc(): FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 should_failslab+0x5/0x20 kmem_cache_alloc_trace+0x57/0x300 ? anon_inode_getfile+0xe5/0x170 media_request_alloc+0x339/0x440 media_device_request_alloc+0x94/0xc0 media_device_ioctl+0x1fb/0x330 ? do_vfs_ioctl+0x6ea/0x1a00 ? media_ioctl+0x101/0x120 ? __media_device_usb_init+0x430/0x430 ? media_poll+0x110/0x110 __se_sys_ioctl+0xf9/0x160 do_syscall_64+0xf3/0x1b0 When that allocation fails, filp->private_data is left uninitialized which media_request_close() does not expect and crashes. To avoid this, reorder media_request_alloc() such that allocating the struct file happens as the last step thus media_request_close() will no longer get called for a partially created media request. Reported-by: syzbot+6bed2d543cf7e48b822b@syzkaller.appspotmail.com Cc: stable@vger.kernel.org Signed-off-by: Tuomas Tynkkynen Fixes: 10905d70d788 ("media: media-request: implement media requests") Reviewed-by: Hans Verkuil Signed-off-by: Sakari Ailus Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Greg Kroah-Hartman --- drivers/media/mc/mc-request.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) --- a/drivers/media/mc/mc-request.c +++ b/drivers/media/mc/mc-request.c @@ -296,9 +296,18 @@ int media_request_alloc(struct media_dev if (WARN_ON(!mdev->ops->req_alloc ^ !mdev->ops->req_free)) return -ENOMEM; + if (mdev->ops->req_alloc) + req = mdev->ops->req_alloc(mdev); + else + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) + return -ENOMEM; + fd = get_unused_fd_flags(O_CLOEXEC); - if (fd < 0) - return fd; + if (fd < 0) { + ret = fd; + goto err_free_req; + } filp = anon_inode_getfile("request", &request_fops, NULL, O_CLOEXEC); if (IS_ERR(filp)) { @@ -306,15 +315,6 @@ int media_request_alloc(struct media_dev goto err_put_fd; } - if (mdev->ops->req_alloc) - req = mdev->ops->req_alloc(mdev); - else - req = kzalloc(sizeof(*req), GFP_KERNEL); - if (!req) { - ret = -ENOMEM; - goto err_fput; - } - filp->private_data = req; req->mdev = mdev; req->state = MEDIA_REQUEST_STATE_IDLE; @@ -336,12 +336,15 @@ int media_request_alloc(struct media_dev return 0; -err_fput: - fput(filp); - err_put_fd: put_unused_fd(fd); +err_free_req: + if (mdev->ops->req_free) + mdev->ops->req_free(req); + else + kfree(req); + return ret; }